The use of color conversion layers is a known method for generating a spectrum of a desired light color or light color mixture from the usually monochromatic radiation that is primarily generated by the OLED. An aim here may be to generate white light and, in particular, light approximated to daylight, which is best suited for lighting purposes.
For LEDs, color conversion layers are known which contain a colorant that is dispersed into a polymer layer and is able to absorb the primary radiation of the LED and to generate a longer-wave secondary radiation. By means of a combination of three color conversion layers having suitably chosen emission wavelengths of the secondary radiation or colorants suitable for this, an approximation to daylight is possible by color mixing of the emission wavelengths. In this case, the thickness of the individual color conversion layers and the concentration of the colorants dispersed therein also have to be selected in a suitable manner.
For the use of these known color conversion layers in OLEDs, however, it is disadvantageous that with their colorants and the polymer matrix, further sensitive material is incorporated into the OLED, which further reduces the lifetime of these components or accelerates the reduction of the luminous intensity as a result of decomposition of the organic constituents. Furthermore, different aging of the different color conversion layers leads to a prematurely commencing undesirable color variation of the resulting total spectrum emitted.